1. Field of the Invention
The present invention relates to a resonator incorporated in a baseplate of an integrated circuit module.
2. Description of the Related Art
Waveguide resonators are designed to operate at a resonant or natural frequency and store oscillating energy that is oscillating at or near the resonant frequency for time periods that are long relative to a period of the resonant frequency. Oscillating energy that is not oscillating at or near the resonant frequency is not stored for an appreciable amount of time. Resonators are described in terms of their quality factor Q which is dependent on a ratio of the maximum stored energy to the energy dissipated per cycle at a given frequency. Cavity resonators generally exhibit the highest Q values. However, the size of the cavity required to produce the desired resonant frequency makes it difficult to mount and connect to an integrated circuit module. For this reason, thin film resonators and dielectric resonators are used instead of cavity resonators because they are easier to attach to integrated circuit modules as discrete components. The use of thin film resonators or dielectric resonators instead of cavity resonators facilitates installation of the resonator on an integrated circuit module at the expense of having a lower Q value.
A prior art filter having cavity resonators is disclosed in U.S. Pat. No. 5,799,247 for use with radio equipment in which cavity resonators are included in the design of a shell for the body of the radio equipment. In this device, the shell is designed to include the required size of the cavity. To accommodate the depth of the cavity, which is larger than the thickness of the shell, the shell includes an expanded portion formed with a large enough depth to house the cavity. Accordingly, the shell must be specifically designed for the cavity for a specific circuit. If a resonator with different characteristics is to be used, i.e., for a different application, a new shell must be designed. Furthermore, the printed circuit board on which the circuit is arranged is connected to a different portion of the shell. Therefore, the resonator still requires external connections to both the input and output of the resonator.
It is an object of the present invention to provide a cavity resonator as an integral part of an electronic module.
The object of the present invention is achieved by an assembly for supporting a substrate of an integrated circuit that includes a baseplate for supporting the substrate and a cavity resonator having a cavity embedded in the baseplate. An excitation coupling of the cavity resonator is connectable to the integrated circuit of the substrate that is supportable on the baseplate. The substrate itself is mounted on the baseplate so that it covers the cavity and is therefore, an integral part of the cavity. The substrate may comprise a multi-layer substrate such as a laminate printed circuit board, a ceramic circuit board, or a thin film circuit board.
The baseplate comprises a material consisting of one of Kovar, CuW, and CuMo. The cavity of the cavity resonator may be circular or rectangular. However, a circular shape is preferred because it is easier to machine into the baseplate.
A tuner, such as a screw plunger, may be arranged in said baseplate for adjusting the resonant frequency of the cavity resonator.
The integrated circuit is mounted on the substrate and may be one of a flip chip, a bond chip, and a monolithic microwave integrated circuit.
The assembly of the present invention may further comprise a metal structure on which the baseplate is mounted. The metal structure may be a heat sink for the integrated circuit and substrate. Furthermore, the metal structure may include a waveguide for connecting the substrate to a further component, such as an antenna filter of a transmitter or receiver.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.